1. Field of the Invention
The present invention relates generally to chucks, and more particularly to an over-center self-adjusting, equalizing cap chuck adapted for high-speed capping operations of bottle caps, especially bottle caps having a serrated outer periphery.
2. Description of the Related Art
The filling and capping process generally entails supplying containers along a conveyor, automatically filling them at a filling station, and automatically capping them at a capping station. Various testing and control functions may also be performed along the way. The apparatus that performs the process must be capable of accommodating a wide variety of containers and caps (both caps and containers may vary in size and shape), and this is accomplished by a universal chuck which allows quick and easy grasping and manipulation of different cap sizes.
Current common methodology for screw cap positioning and torque include the tapered chuck, the friction disk chuck, the donut chuck, and the segmented chuck, a description of which and the shortcomings of which may be found at the background art discussion of U.S. Pat. No. 6,170,232 to VandeGeijn. Thus, various designs have been suggested for bottle capping chucks.
The development of high-speed machining applications have required bottle capping chucks to operate at significantly higher rotational speeds for caps of varying size and characteristics, such as wall thickness and flexibility. Thus, adjustable chucks of the type in widespread use for gripping work pieces of different sizes typically include a number of internal moving parts, including, for example rocker arms, swivel mountings, bearings, slide members, toggle links, equalizing plates, and other complementary components interactive with each other, which serve to open and close or interact with the gripping jaws. Smooth operation of these parts is most important to assure that a positive clamping of the work piece is achieved when the jaws are closed, and further that each of the jaws applies equal pressure against work piece to prevent distortion and possible eccentric location of the work piece. Illustrative of such chucks are those designs disclosed in U.S. Pat. No. 6,665,699 to Grobbel, and U.S. Pat. Nos. 6,206,382 and 5,941,538 to Gonnocci.
The speeds at which chucks are used in moderate manufacturing processes have placed increasing importance upon the rotational balance of the chuck and the work piece held therein. For example, an imbalance may cause improper machining which results in rejection of the work piece. Alternatively, an imbalance may create a change in the gripping force as a result of the centrifugal force created by the rotation of the gripping jaw. Thus, it is desirable to provide a chuck which maintains a proper balance and constant gripping force independent of a capping machine's rotational spindle assembly speed, is selectively self-adjusting to allow light engagement of the cap and containers threads and to provide light contact between the threads during rotation of the cap, and is readily adjustable to variations in cap size and characteristics to insure undamaged concentric alignment during capping operations.
Additionally, it would be advantageous if a self-adjusting cap chuck addressing the foregoing needs could be used in a variety of capping machinery by ready adaptation to a spindle assembly thereof. Indeed, the entirety of U.S. Pat. No. 6,240,678 to Spether, U.S. Pat. No. 6,170,232 to VaneGeijn, U.S. Pat. No. 5,417,031 to Bankuty et al., and U.S. Pat. No. 5,135,242 to Toth are hereby incorporated by reference for their general teachings of capping machinery utilizing cap chucks.